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Earth Science Chapter 10 and 11 SJS 7th Grade

Join our class as we explore the fascinating aspects of earthquakes and mountain building! Learn about P-waves, S-waves, faults, horsts, folds, and more! doesn't that sound cheesy?
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earthquake
the shaking of Earth's crust caused by a release of energy
Causes of earthquakes
eruption of a volcano, collapse of cavern, impact of meteor, for most it is the strain that builds up along faults
fault
break in the lithosphere along which movement has occured
elastic-rebound theory
theory that describes when the plates deform through stress, and then move suddenly and snap back to original form, but moved relative to each other.
focus
point at which first movement of an earthquake occurs
epicenter
point on Earth's surface directly above the place where first movement occurs
divergent
type of boundary where earthquakes are shallow
transform
type of boundary where earthquakes are also shallow
subduction
type of boundary where earthquakes are deep
body waves
waves that travel from the focus of an earthquake through Earth
P waves
waves that squeeze and stretch rock as they pass through Earth- can travel through any material
S waves
shear waves that cause material to move at right angles to the direction in which the waves are traveling, cannot travel through liquids or gases
density
the rate at which body waves move depends on the type and ____________ of the material through which they travel
greater
the velocity of body waves is ________ when they are traveling through rigid and dense material
surface waves
earthquake waves that travel along Earth's surface
Love waves
cause particles to move from side to side, perpendicular to direction of wave movement
Rayleigh waves
travel more slowly than the other type of surface waves, cause particles of material to move in elliptical patterns, ripples
seismograph
instrument that detects and records waves produced by earthquakes that may have originated hundreds of kilometers away
seismogram
record sheet that is placed on a drum attached to the base
travel-time graph
shows the relationship between P-wave and S-wave arrival time and the distance from an earthquake's epicenter
three
number of seismographs needed to determine the location of an earthquake
magnitude
measure of amount of energy released in an earthquake
Richter scale
measures intensity of ground movements, each whole number increase is a 31-fold increase in energy
moment magnitude
a measure that more accurately indicates the total energy involved in an earthquake, takes everything into consideration
liquefaction
occurs when loose soil temporarily takes on some of the properties of a liquid
aftershocks
a series of smaller earthquakes that occur after a major earthquake originating close to the focus of the larger one
tsunami
underwater earthquakes and landslides cause huge ocean waves, a ____________.
depth
The speed of a tsunami depends upon the ________ of the water
New Madrid
earthquake that occurred along the Mississippi River in Missouri, it was not along a fault, sediments in Mississippi, Ohio, and Missouri Rivers cause faults
seismic gaps
areas where a fault has not moved for a long period of time, places where stress is building up and an earthquake is expected to happen
shadow zone
area on Earth where seismographs do not detect P waves and S waves after an earthquake
Moho
area in Earth where the dense rock of the mantle meets the less dense rock of the crust
transition zone
separates the upper mantle from the denser lower mantle
mountain
large mass of rock that rises a great distance about its base
mountain belts
long belts that tend to follow convergent plate boundaries
continental margin
boundary between continental crust and oceanic crust
active
continental margin that occurs along a plate boundary
passive
continental margin that does not occur along a plate boundary
sediment
accumulates along passive continental margins
stress
measure of the amount of force applied over a given area
compression
stress that involves squeezing
tension
stress that involves pulling and stretching
shearing
stress that involves forces moving in opposite directions
fracture
happens when stress is applied to rocks at earth's surface
folds
during plate collisions, stress can cause rock layers along continental margins to crumple into __________.
beneath
Folding occurs ________ Earth's surface
anticline
upfold in the rock layers
syncline
downfold in the rock layers
limbs
the two sides of a fold
dip
steepness of limbs, reflects intensity of folding
strike
compass direction of fold
hanging wall
part of fault above the fault plane
footwall
part of fault below the fault plane
normal fault
hanging wall moves down relative to the footwall, tension
reverse fault
hanging wall moves up relative to the footwall, compression
thrust fault
reverse faults where the fault plane dips 45 degrees or less from the horizontal, compressive stresses can move rock great distances
strike-slip fault
rocks on opposite sides of the fault plane move horizontally past each other; San Andreas fault
joint
unlike a fault, a _____ is a break without movement
joint set
joints appear on the surface of a rock outcrop as a line, these lines can appear in parallel groups called ________ _____.
folded mountains
when two plates carrying continental crust collide, rocks can fold and crumple into ______ __________
dome mountain
nearly circular folded mountain, individual, isolated structures that tend to occur in areas of essentially flat-lying sedimentary rocks, bent upward in a dome shape as a result of uplifting forces
plutonic
type of dome mountain, igneous intrusion, youngest rock at center
tectonic
type of dome mountain, uplifting forces arch rock upward, youngest rocks on edge
fault-block mountains
formed by tension, uplift
horsts
a block of crust is thrown up between two normal faults
grabens
large blocks of crust have dropped between two normal faults
Marcoli scale
scale to measure earthquake based on people's observations